1. Field of the Invention
The present invention relates to the production of mercaptans from thioethers and hydrogen sulfide in the presence of appropriate catalysts.
2. Background Art
The industrial interest in mercaptans is such that numerous studies have been conducted with a view to perfecting synthesis of these compounds. The processes most widely used in practice are based on the reaction of H.sub.2 S with alcohols or with olefins. In the majority of cases, the main by-products obtained are thioethers, formed mainly by reaction of the mercaptans with the alcohols or with the olefins, depending on the process used. Aside from a small number of thioethers, the symmetric thioethers obtained in the synthesis of mercaptans generally have no commercial value.
Methods of conversion of these thioethers have been proposed to transform them into corresponding mercaptans by reaction with hydrogen sulfide in the presence of different catalysts.
However, despite certain improvements achieved (more efficient catalysts, introduction of carbon disulfide as promotor . . . ), these reactions necessitate elevated temperatures (250.degree. to 360.degree. C.) and lead to the formation of undesirable by-products, which have the consequence of appreciably lowering the mercaptan selectivity.
The present invention provides a new process, the principal advantages of which are very high mercaptan yield and selectivity, and the possibility of obtaining easily primary and secondary mercaptans.